[lugerholsterrepair]

Arjan, Yes..Vlim is Gerben. Your pistol is from several other pistols put together so determining a date of manufacture is a moving target.

The stock lug tells us the pistol frame is likely to have been made after 1913. There were frames made with stock lugs before that such as commercials or Navies but there are no Naval or commercial markings on your frame..or even Military so it's a crapshoot guessing when it might have been manufactured.

The Erfurt parts...Likely wartime manufactured. say 1914-1918

The Police conversion..1918-1930 give or take.

Any or all of this is pretty much conjecture..The broadest range would run from say..1906 to 1933 or so. Just not enough clues IMO to nail it down real tight.